Fix WebAssemblySpillPointers crash at O2: move pass before PEI#4
Merged
PLUTOFX merged 2 commits intorelease/16.xfrom Feb 28, 2026
Merged
Conversation
…tRegAlloc The SpillPointers pass was crashing at O2 because: 1. It created frame indices (via CreateSpillStackObject + addFrameIndex) in addPreEmitPass(), but PEI had already run and wouldn't resolve them 2. It required LiveIntervals after RegColoring had invalidated it Fix: Move the pass to addPostRegAlloc() where it runs before PEI, so frame indices are properly resolved. Also remove addPreserved for LiveIntervals since the pass inserts new STORE instructions. Co-authored-by: PLUTOFX <110596339+PLUTOFX@users.noreply.github.com>
Copilot
AI
changed the title
[WIP] Fix frontend compilation error with O2 optimization
Fix WebAssemblySpillPointers crash at O2: move pass before PEI
Feb 28, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
WebAssemblySpillPointerscrashes at O2 because it runs inaddPreEmitPass()— after PEI has already completed. The pass creates new frame indices (CreateSpillStackObject+addFrameIndex) that PEI never resolves, and requiresLiveIntervalsthatRegColoringhas already invalidated.Changes
addPreEmitPass()toaddPostRegAlloc()— runs before PEI, so frame indices are resolved normallyaddPreserved<LiveIntervals>()— the pass inserts STORE instructions, so claiming preservation was incorrectPipeline ordering (before → after)
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.